Various species of algae are now being commercially grown for a variety of uses including bio-fuel feedstock and health supplements, among others. Algae are desirable in that they can be grown year round under the right temperature conditions, have relatively short generation times, and require readily available and inexpensive nutrients for growth, such as sunlight, water and carbon dioxide. Algae are also desirable in that they can be grown in adverse conditions, such as saline and brackish water.
Algae are typically grown in open bio-ponds and shallow raceways in which it is necessary to create a current to prevent the algae from becoming stagnant. It is also necessary to prevent algae from remaining at the surface of the pond in which sunlight exposure may be too great, or remaining at the bottom of the pond in which there is too little sunlight exposure, both of which are adverse to growth. Conventionally, to address these issues, paddlewheels have been deployed within ponds and raceways to introduce a current. These conventional paddlewheel designs, however, suffer from several disadvantages, some of which include utilizing large flat paddles that require large amounts of energy to move through the water, paddle structures that are cupped in the direction of rotation and retain water as the paddles leave the water, and paddlewheels that are fixed in height in relation to the pond floor, thus causing cavitation and the raising of liners in lined ponds.
Accordingly, to overcome the disadvantages of conventional paddlewheel designs, and to improve the creation of current in a bio-pond or raceway, a paddlewheel apparatus and methods of operation are provided that include an energy efficient paddle design, height adjustability, sensor control to optimize paddlewheel rotational speed and construction including materials adapted to withstand both fresh and salt water conditions.